1. Field of the Invention
The present invention relates to a laser processing system including a laser optical path that guides laser beam emitted from a laser oscillator to an object to be processed.
2. Description of the Related Art
When such impure gases as to disperse or absorb laser beam is present around a laser oscillator, a large influence on the propagation of the laser beam is generated. Accordingly, in a conventional laser processing system in which the laser oscillator is mounted, a laser optical path including an optical system that guides the laser beam from a beam emission port of the laser oscillator to a processing point is provided. Moreover, such a laser optical path is filled with a clean purge gas that fails to influence the propagation of the laser beam, which allows laser processing to be stable.
Further, Japanese Patent Publication No. 4335154 discloses an invention of the conventional laser processing system as described above, in which a gas sensor for detecting impure gases is provided in the laser optical path to determine whether or not the impure gases were mixed in the laser optical path.
Moreover, in the invention disclosed in Japanese Patent Publication No. 4335154, the impure gases as described above that were mixed in the laser optical path are discharged out of the laser optical path by allowing a clean purge gas, such as nitrogen-rich gas that contains nitrogen as a main component, nitrogen gas and the like, to flow in the laser optical path. Further, Japanese Patent Publication No. 4335154 discloses, as the impure gases as described above, carbon dioxide and an organic solvent gas, such as ethanol or ammonia.
However, according to the invention disclosed in Japanese Patent Publication No. 4335154, a time needed for the purge gas to decrease concentrations of the organic solvent impure gases, such as ethanol, to concentrations at which laser processing is enabled is longer in comparison with a case in which the impure gases are carbon dioxide. A cause thereof is presumed to lie in that the organic solvent impure gases as described above are pseudo-chemically bonded to a wall surface in the laser optical path. In other words, the invention disclosed in Japanese Patent Publication No. 4335154 has a problem in that, when the organic solvent impure gases, such as ethanol, were mixed in the laser optical path, it will be difficult to promptly discharge the impure gases out of the laser optical path.